The present invention relates to a thickening agent comprising a hydroxyalkylated-carboxymethylated tamarind seed powder or tamarind gum suitable for a printing paste or binding paste.
Tamarind (Tamarindus Indica) is a leguminous evergreen tall tree produced in the tropics. Tamarind seed powder is obtained by grinding the seeds of tamarind from which the testa is removed. Tamarind gum is obtained by extracting and purifying the seed powder.
It is known that a reaction product prepared by subjecting a tamarind seed powder or gum to only hydroxyalkylation or a reaction product prepared by subjecting a tamarind seed powder or gum to only carboxymethylation is useful as a thickening agent for industrial pastes, for example, printing paste in textile industry and binding paste in paper industry (DE-AS No. 1,108,198, U.S. Pat. No. 3,223,699 and U.S. Pat. No. 4,089,646).
When the above-mentioned products are used in a printing paste, they are so much poor in compatibility with direct dyes, acid dyes or metal complex dyes, since they react with such dyes to gel. When the products are used in cotton printing employing reactive dyes, the wash-off property of the paste is lowered due to the reaction of them with the reactive dyes.
When the products are used in a binding paste, they exhibit a somewhat binding property but the property is inferior to that of starch widely used as a binding agent.